Clearfield Rice Production System In Honduras

Honduras is about to embark on a rice cultivation program that will likely increase short term yields, but holds the potential to devastate the rice industry in Honduras if strict protocols are not observed.

The key to the potential increased yields, and the danger, is a variety called Clearfield rice.

Beneficio de Arroz Progreso, S.A. de C.V. has signed an agreement with BASF, a German company licensed to sell Clearfield rice varieties along with two herbicides necessary for its successful cultivation, Newpath and Clearpath, to begin using Clearfield rice in Honduras.

Clearfield rice has a natural mutation that causes it to be resistant to the herbicide Imidazolinone, known by trade names including Clearpath and Newpath. This rice was developed at the LSU Agriculture Center and developed commercially by Horizon Ag, a rice seed company.

What Clearfield rice is supposed to address is an energetic weed, red rice, that out-competes rice in fields, and lowers the quality (and hence the price) for harvested rice. Red rice (Oryza punctata) is a separate species in the rice family, close enough to domesticated rice (Oryza sativa) that any of the herbicides that kill red rice also kill domesticated rice. Clearfield rice is selected for resistance to specific herbicides that currently can kill red rice.

The rice farmer can use two applications of Imidazolinone-based herbicides to control red rice in the field without harming the Clearfield rice, while eliminating the red rice in the field.

The presence of red rice growing in domestic rice fields degrades the quality of the harvested rice crop. Rice from fields with red rice intermixed must be milled twice, first to remove the husks, then a second time to remove the red rice. This additional milling leads to more broken kernels, and hence a lower grade designation, for the finished product.

But because red rice is a member of the rice family (the genus Oryza), there is a danger of hybridization. When red rice grows in proximity to Clearfield rice, the gene the conveys resistance to the herbicide, which is dominant, passes to up to 0.46% of the offspring.

That's not good, because then the weed has the same resistance as the rice itself.

To avoid this problem a specific, complicated, and expensive protocol was developed by Horizon Ag and BASF. This Clearfield rice production system requires that the grower make two applications of Clearpath and Newpath herbicides during the growing season.

After harvest the farmer must rotate crops to a glycophosphate (think RoundUp) resistant crop, and treat the field with that for another year. Red rice in surrounding irrigation ditches must be treated with Beyond herbicide. The goal is to nearly eradicate red rice in the rice field itself, then let any red rice that survives and goes to seed sprout and be eradicated in the subsequent year, before returning to Clearfield rice again in the field.

The herbicides are toxic to fish and aquatic invertebrates according to the Materials Safety Data Sheet, and don't biodegrade. So water in the field must be contained and not dumped into the local drainages. Likewise, workers must be protected from inhaling, eating, or getting these herbicides on their skin.

No saving seed from this rice, either.

The benefit is that Clearfield varieties yield a higher quality of rice, promising a higher price per pound. But this benefit will only be realized if the full protocol is observed. Hybrid varieties of domestic rice crossed with Clearfield rice also offer increased yields, which would increase income per unit of area planted. However, if resistant red rice develops, there is no herbicide that will kill it without also killing the commercializable rice.

If a resistant red rice escapes from a farm under the Clearfield protocal, rice quality, and hence price, will decline; there will be no treatment to reduce red rice in growing fields that does not also harm the growing rice. Such an event could put an end to the commercial viability of rice production in Honduras.